This invention relates to a lubricant construction for a marine propulsion device of the water jet type and more particularly to an improved gear casing and lubricating system for a marine outboard drive.
In many forms of marine outboard drives, it is well known to include a bearing arrangement for supporting and sustaining the axial and radial loads of a driving shaft. This type of drive is employed in outboards of the conventional propeller type or also those of the jet propulsion type. In order to insure long life and cooling of the bearings, it is normally the practice to pack the bearings with a grease type lubricant. There are a number of disadvantages to such an arrangement.
In the first instance, the grease is not as effective in lubricating and cooling the bearings as is a lubricating oil. In addition, the leakage problems associated with grease are well known. Leakage occurs due to the fact that the grease expands when it is heated and can force it out of the seals which are provided to contain the grease. Furthermore, the grease must be replaced quite often (such as every ten hours of running or so) and this requires substantial disassembly of the outboard drive in order to extract and repack the bearings. Furthermore, when the bearings are disassembled and must be reassembled, this requires a certain degree of skill so as to insure that the bearings are properly located. In addition, the repacking of bearings is not as simple a job as it appears since it must be insured that all of the old grease is removed and fresh grease is inserted without the entrainment of foreign matter during the repacking process.
It is, therefore, a principal object of this invention to provide an improved lubricating system for the bearings of a marine outboard drive.
It is a further object of this invention to provide a lubricating system for the bearings of a marine outboard drive wherein a lubricating oil rather than a lubricating grease may be used.
One of the reasons why lubricating oil has not been previously used to any wide extent for the bearings of a marine outboard drive is the difficulties in changing the lubricant. That is, it must be insured that all of the lubricant is drained and replaced each time the bearings are relubricated. Thus, many of the same problems attendant with changing of the lubricating grease are also incurred when lubricating oil is utilized. It must be understood that the marine outboard drive may, in many instances, be relatively permanently attached to the transom of the associated watercraft, even when the outboard drive comprises an outboard motor.
Therefore, it is a still further object of this invention to provide an improved lubricating system for the bearings of a marine outboard drive in which lubricating oil is employed and in which the lubricating oil may be completely drained and refilled with the outboard drive in position.